Center fed open ended waveguide (OEWG) antenna arrays

ABSTRACT

Example radar systems are presented herein. A radar system may include radiating elements configured to radiate electromagnetic energy and arranged symmetrically in a linear array. The radiating elements comprise a set of radiating doublets and a set of radiating singlets. The radar system also includes waveguide configured to guide electromagnetic energy between each of the plurality of radiating elements and a waveguide feed. The waveguide feed is coupled to the second side of the waveguide at a center location between a first half of the plurality of radiating elements and a second half of the plurality of radiating elements. The waveguide feed is configured to transfer electromagnetic energy between the waveguide and a component external to the waveguides. The radar system may also include a power dividing network defined by the waveguide and configured to divide the electromagnetic energy transferred by the waveguide feed based on a taper profile.

CROSS REFERENCE TO RELATED APPLICATION

The present patent application is a continuation-in-part of U.S. patentapplication Ser. No. 16/230,702, filed on Dec. 21, 2018, which is herebyincorporated by reference in its entirety.

BACKGROUND

Radio detection and ranging (RADAR) systems can be used to activelyestimate distances to environmental features by emitting radio signalsand detecting returning reflected signals. Distances to radio-reflectivefeatures can be determined according to the time delay betweentransmission and reception. A radar system can emit a signal that variesin frequency over time, such as a signal with a time-varying frequencyramp. The radar system can then relate the difference in frequencybetween the emitted signal and the reflected signal in order to derive arange estimate of the object or surface that reflected the emittedsignal.

Some radar systems may also estimate relative motion of reflectiveobjects based on Doppler frequency shifts in the received reflectedsignals. In addition, a radar system may incorporate directionalantennas for the transmission and/or reception of signals in order toassociate each range estimate with a bearing. The directional antennascan also be used to focus radiated energy on a given field of view ofinterest enabling the surrounding environment features to be mappedusing the radar system.

SUMMARY

In one aspect, the present application describes a system. The systemmay include a plurality of radiating elements configured to radiateelectromagnetic energy and arranged in a linear array. The system alsoincludes a waveguide feed and a waveguide configured to guideelectromagnetic energy between (i) each of the plurality of radiatingelements and (ii) the waveguide feed. The waveguide comprises a firstside and a second side opposite the first side, where the radiatingelements are coupled to the first side of the waveguide. The waveguidefeed is coupled to the second side of the waveguide at a center locationbetween a first half of the plurality of radiating elements and a secondhalf of the plurality of radiating elements. The waveguide feed isconfigured to transfer electromagnetic energy between the waveguide anda component external to the waveguide.

In another aspect, the present application describes a method. Themethod may involve feeding electromagnetic energy to a center of awaveguide by a waveguide feed. The waveguide comprises a first side anda second side opposite of the first side. The method may further involvepropagating electromagnetic energy via the waveguide between (i) each ofa plurality of radiating elements and (ii) the waveguide feed. Theplurality of radiating elements is arranged in a linear array andcoupled to the first side of the waveguide. The method also includes,for each radiating element, providing a portion of the propagatingelectromagnetic energy and radiating at least a portion of thepropagating electromagnetic energy via each radiating element.

In yet another aspect, the present application describes a radar system.The radar system includes a plurality of radiating elements configuredto radiate electromagnetic energy and arranged in a linear array. Theplurality of radiating elements comprises a set of radiating doubletsand a set of radiating singlets. The radar system further includes awaveguide feed and a waveguide configured to guide electromagneticenergy between (i) each of the plurality of radiating elements and (ii)the waveguide feed. The waveguide comprises a first side and a secondside opposite the first side, where the plurality of radiating elementsis coupled to the first side of the waveguide. The waveguide feed iscoupled to the second side of the waveguide at a center location betweena first half of the plurality of radiating elements and a second half ofthe plurality of radiating elements. The waveguide feed is configured totransfer electromagnetic energy between the waveguide and a componentexternal to the waveguide.

In still another aspect, a system is provided that includes means forradiating electromagnetic energy. The system includes means for feedingelectromagnetic energy to a center of a waveguide by a waveguide feed.The waveguide comprises a first side and a second side opposite of thefirst side. The system further includes means for propagatingelectromagnetic energy via the waveguide between (i) each of a pluralityof radiating elements and (ii) the waveguide feed. The plurality ofradiating elements is arranged in a linear array coupled to the firstside of the waveguide. The system includes means for providing a portionof the propagating electromagnetic energy for each radiating element.The system also includes means for radiating at least a portion of thepropagating electromagnetic energy via each radiating element.

In another aspect, the present application describes an antenna system.The antenna system includes a first layer having a first portion of afeed waveguide coupled to a feed port. The antenna system also includesa second layer having a second portion of the feed waveguide and a firstportion of a waveguide. The first portion of the feed waveguide iscoupled to the second portion of the feed waveguide such that the feedwaveguide causes propagation of electromagnetic energy in a directionparallel to a seam between the first layer and the second layer. Inaddition, the second portion of the feed waveguide is coupled to thefirst portion of the waveguide at a coupling point. The antenna systemfurther includes a third layer having a second portion of the waveguideand a set of radiating elements arranged in a linear array. Eachradiating element is coupled to the second portion of the waveguide, andwherein the coupling point aligns with a center of the linear array.

In a further aspect, the present application describes another method ofradiating radar. The method involves feeding, at an antenna system,electromagnetic energy to a center of a waveguide by a feed waveguide. Afirst layer of the antenna system includes a first portion of the feedwaveguide coupled to a feed port. The method further involvespropagating electromagnetic energy via the waveguide between (i) thefeed waveguide and (ii) each of a set of radiating elements arranged ina linear array. A second layer of the antenna system includes a secondportion of the feed waveguide and a first portion of the waveguide.Particularly, the first portion of the feed waveguide is coupled to thesecond portion of the feed waveguide such that the feed waveguide causespropagation of electromagnetic energy in a direction parallel to a seambetween the first layer and the second layer. In addition, the secondportion of the feed waveguide is coupled to the first portion of thewaveguide at a coupling point. The method also involves, for eachradiating element, providing a portion of the propagatingelectromagnetic energy. A third layer of the antenna system includes asecond portion of the waveguide and the set of radiating elementsarranged in the linear array. Each radiating element is coupled to thesecond portion of the waveguide and the coupling point aligns with acenter of the linear array. The method further involves radiating atleast a portion of the propagating electromagnetic energy via eachradiating element.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the figures and the followingdetailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A illustrates a first configuration of an antenna, in accordancewith example embodiments.

FIG. 1B illustrates a second configuration of an antenna, in accordancewith example embodiments.

FIG. 1C illustrates a three-dimensional rendering of the secondconfiguration of the antenna shown in FIG. 1B, in accordance withexample embodiments.

FIG. 2A illustrates a first layer of an antenna, in accordance withexample embodiments.

FIG. 2B illustrates another assembled view of the antenna, in accordancewith example embodiments.

FIG. 3 illustrates a wave-radiating portion of an antenna, in accordancewith example embodiments.

FIG. 4 illustrates a waveguide portion of the antenna, in accordancewith example embodiments.

FIG. 5 is a flowchart of a method, in accordance with exampleembodiments.

FIG. 6 illustrates a three layer center-fed antenna configuration, inaccordance with example embodiments.

FIG. 7 illustrates a three-dimensional rendering of the three layercenter-fed antenna configuration illustrated in FIG. 6, in accordancewith example embodiments.

FIG. 8 is a flowchart of a method, in accordance with exampleembodiments.

FIG. 9 is a flowchart of another method, in accordance with exampleembodiments.

DETAILED DESCRIPTION

in the following detailed description, reference is made to theaccompanying figures, which form a part hereof. In the figures, similarsymbols typically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, figures, and claims are not meant to be limiting. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the scope of the subject matter presented herein. It willbe readily understood that the aspects of the present disclosure, asgenerally described herein, and illustrated in the figures, can bearranged, substituted, combined, separated, and designed in a widevariety of different configurations, all of which are explicitlycontemplated herein.

A radar system may operate at an electromagnetic wave frequency in theW-Band, for example 77 Giga-Hertz (GHz), resulting in millimeter (mm)electromagnetic wave length (e.g., 3.9 mm for 77 GHz). The radar systemmay use one or more antennas to focus radiated energy into tight beamsto measure a nearby environment. The measurements can be captured withhigh precision and accuracy. For instance, the radar system a capturemeasurements of the environment around an autonomous vehicle. Suchantennas may be compact (typically with rectangular form factors),efficient (i.e., there should be little energy lost to heat in theantenna, or reflected back into the transmitter electronics), andinexpensive and easy to manufacture.

Efficiency can be difficult to achieve in inexpensive, easy tomanufacture radar systems. Some inexpensive and easy to manufactureoptions involve integrating an antenna onto a circuit board (e.g., witha “series-fed patch antenna array). This antenna configuration, however,might lose energy due to the substrate of the circuit board absorbingenergy. One technique often used to reduce energy loss involvesconstructing an antenna using an all-metal design. Conventionalall-metal antenna designs (e.g., slotted waveguide arrays), however,might be difficult to manufacture in a manner that incorporates minimalgeometries needed to enable 77 GHz operation.

The following detailed description discloses example “open-endedwaveguide” (OEWG) antennas for a radar system and methods forfabricating such antennas. The radar system may operate for anautonomous vehicle or another type of navigating entity. In someexamples, the term “OEWG” may refer herein to a short section of ahorizontal waveguide channel plus a vertical channel. The verticalchannel may split into two parts, where each of the two parts of thevertical channel includes an output port configured to radiate at leasta portion of electromagnetic waves that enter the antenna. Thisconfiguration may be a dual open-ended waveguide. In other examples, thevertical channel itself may form the output as a single element.

An example OEWG antenna may be generated using two or more metal layers(e.g., aluminum plates) machined with computer numerical control (CNC),aligned properly, and joined together. The first metal layer may includea first half of an input waveguide channel. As such, the first half ofthe first waveguide channel may further include an input port that maybe configured to receive electromagnetic waves (e.g., 77 GHz millimeterwaves) into the first waveguide channel.

The first metal layer may also include a first half of a plurality ofwave-dividing channels. The wave-dividing channels may include a networkof channels that branch out from the input waveguide channel andconfigured to receive electromagnetic waves from the input waveguidechannel, divide the electromagnetic waves into portions ofelectromagnetic waves (i.e., power dividers), and propagate the portionsof electromagnetic waves to wave-radiating channels. As such, the twometal layer configuration may be called a split block construction.

The first metal layer may be configured with a first half of thewave-radiating channels that are configured to receive portions ofelectromagnetic waves from wave-dividing channels. The first halves ofthe wave-radiating channels include at least one wave-directing memberconfigured to propagate sub-portions of electromagnetic waves to anothermetal layer.

Moreover, the second metal layer making up the antenna may includesecond halves of the input waveguide channel, the wave-dividingchannels, and the wave-radiating channels. The second halves of thewave-radiating channels may include one or more output ports partiallyaligned with one or more one wave-directing members. Each wave-directingmember may be configured to radiate sub-portions of electromagneticwaves propagated from the one or more wave-directing members out of thesecond metal layer. As such, a combination of a given wave-directingmember with a corresponding pair of output ports may take the form of(and may be referred to herein as) a OEWG, as described above. While inthis particular example the antenna includes multiple wave-dividingchannels and multiple wave-radiating channels, in other examples theantenna may include, at a minimum, only a single channel configured topropagate all the electromagnetic waves received by the input port toone or more wave-radiating channels. For instance, all or a portion ofthe electromagnetic waves may be radiated out of the second metal layerby a single OEWG. Other examples are possible as well.

The antenna may further include a waveguide feed coupled on the oppositeside of the waveguide from the element feeds for each of the radiatingelements. For instance, the element feed or feeds may be located on thetop of the waveguide and the waveguide feed may be located on the bottomof the waveguide. During operation of the waveguide in a transmissionmode, the waveguide feed may provide electromagnetic energy to thewaveguide for transmission by the radiating elements. Conversely, duringoperation of the waveguide in a reception mode, the waveguide feed maybe configured to couple electromagnetic energy received from theradiating elements outside of the feed waveguide.

The waveguide feed may be located at a position along the length of thefeed waveguide. For example, in traditional waveguide systems,electromagnetic energy may be fed at one of the ends of the length ofthe waveguide in a direction corresponding to the length of thewaveguide. By feeding a waveguide at the end, power division to achievethe taper profile (i.e., the desired phase and power amplitude for eachradiating element) may be more difficult. As disclosed herein, thewaveguide can instead be fed from the bottom of the waveguide, in adirection orthogonal to the direction of the length of the waveguidethat feeds the radiating elements in some examples. Further, by feedingthe waveguide from the bottom at a point along the length, it may beeasier to design the power splitting network for the system.

In some embodiments, the waveguide feed is coupled to a side of thewaveguide along the length dimension of the waveguide. Particularly, thewaveguide may be positioned at a center location between a first half ofthe radiating elements and a second half of the radiating elements. Thefirst half and second half of the radiating elements may be arrangedsymmetrically in a linear array on the side of the waveguide opposite ofthe waveguide feed. Symmetrically may indicate that the first half ofthe radiating elements and the second half of radiating elements mirroreach other (i.e., have a uniform arrangement) starting from a center ofthe linear array. For instance, each half of the linear array mayinclude the same number of radiating elements and the same type ofradiating elements.

When multiple types of radiating elements make up the linear array(e.g., radiating singlets and radiating doublets), the symmetry of thelinear array may exist with the first half of the linear array and thesecond half of the linear array having the same configuration extendingaway from a center of the linear array. For instance, a linear array mayinclude radiating singlets on both ends and four radiating doubletspositioned in between the radiating singlets. As such, the symmetryexists with a first half having a first radiating singlet on the end andtwo radiating doublets and a second half having a second radiatingsinglet on the opposite end and two radiating doublets as well. In otherexamples, each half of the radiating elements may not be symmetrical.

As indicated above, some embodiments may involve the waveguide feedcoupled to the waveguide at a center position such that the waveguidefeed aligns with a center of the linear array of radiating elements. Assuch, when the waveguide feed is positioned at a center location in themiddle of the radiating elements, the waveguide feed may feedelectromagnetic waves to the radiating elements in a common phaseregardless of frequency. In turn, the antennas can be created to operatewith a wider bandwidth of operation reducing phase issues. In addition,the antennas may also operate with less energy loss.

In some examples, the waveguide feed is positioned to the waveguide inbetween two sets of radiating doublets and two radiating singlets. Thesets of radiating doublets and radiating singlets may be arrangedsymmetrically in a linear array. For instance, the waveguide feed may bepositioned in between a first half of radiating elements consisting oftwo radiating doublets and a first singlet and a second half ofradiating elements consisting of two radiating doublets and a secondsinglet. The singlets of each half of radiating elements may bepositioned at the center of the linear array in between such that tworadiating doublets are outside each side of the singlets. In otherexamples, the singlets may be positioned on the ends of the lineararray. As such, the radiating doublets and the radiating singlets mayoperate with a common phase regardless of frequency. Additionally, insome examples, the waveguide and radiating elements may be symmetricaround the central location of the waveguide feed.

In some embodiments, the two or more metal layers making up an antennamay be joined directly, without the use of adhesives, dielectrics, orother materials, and without methods such as soldering, diffusionbonding, etc. that can be used to join two metal layers. For example,the two metal layers may be joined by making the two layers in physicalcontact without any further means of coupling the layers.

In some examples, the present disclosure provides an integrated powerdivider and method by which each waveguide that feeds a plurality ofradiating elements of a OEWG may have its associated amplitude isadjusted. The amplitude may be adjusted based on a predefined taperprofile that specifies a relative phase and power for each respectiveradiating element. Additionally, the present OEWG may be implementedwith a simplified manufacturing process. For example, a CNC machiningprocess or a metal-coated injection molding process may be implementedto make the above-described adjustments in parameters such as height,depth, multiplicity of step-up or step-down phase adjustment components,etc. Yet further, the present disclosure may enable a much more accuratemethod of synthesizing a desired amplitude and phase to cause a realizedgain, side lobe levels, and beam steering for the antenna apparatus, ascompared to other types of designs.

Furthermore, while in this particular example, as well as in otherexamples described herein, the antenna apparatus may be comprised of twometal layers, it should be understood that in still other examples, oneor more of the channels described above may be formed into a singlemetal layer, or into more than two metal layers that make up theantenna. Still further, within examples herein, the concept ofelectromagnetic waves (or portions/sub-portions thereof) propagatingfrom one layer of a OEWG antenna to another layer is described for thepurpose of illustrating functions of certain components of the antenna,such as the wave-directing members. In reality, electromagnetic wavesmay not be confined to any particular “half” of a channel during certainpoints of their propagation through the antenna. Rather, at thesecertain points, the electromagnetic waves may propagate freely throughboth halves of a given channel when the halves are combined to form thegiven channel.

In practice, for the transmission of radar signals, the present antennamay receive a signal at a port on the bottom of a waveguide block. Thesignal may be evenly split between two different portions of a feedwaveguide. The two different portions of the feed waveguide may besymmetric to one another about a plane centered on the port. Within eachportion of the feed waveguide, the respective split signal may propagatealong the respective portion of the waveguide. At each of a plurality ofantenna feeds coupled to the respective feed waveguide portions, aportion of the signal may be coupled into the feed for transmission byantennas. During the operation of the antenna, the frequency ofoperation of the signal may vary. As the frequency varies, eachrespective set of antennas coupled to a respective feed waveguidesection may have an associated beam squint, that is an undesired tilt ofthe transmitted beam. However, because there are two waveguides that arecommonly fed at a center, the two beam squints may be of the samemagnitude but in opposite directions. Therefore, the superposition ofthe two beams may cause an overall beam pattern to be in the desireddirection, as the two beam squints offset one another. Similarly, theantenna may operate in a similar manner when receiving signals (i.e.,two beam squints may offset one another).

Referring now to the figures, FIG. 1A illustrates a first configurationof an antenna. As shown in the first configuration, the antenna 100includes a set of radiating elements 102, a waveguide 104, and awaveguide feed 110. In other configurations, the antenna 100 may includemore or fewer elements.

The set of radiating elements 102 are shown with the radiating elementsarranged symmetrically in a linear array. Each radiating element isconfigured to radiate electromagnetic energy. For instance, the set ofradiating elements 102 may receive electromagnetic energy from thewaveguide 104 and radiate the electromagnetic energy as radar signalsinto the environment. The radiating elements 102 may also receivereflected signals that reflected off surfaces in the environment andback towards the antenna 100.

The waveguide 104 is configured to guide electromagnetic energy betweenthe set of radiating elements 102 and the waveguide feed 110. As shownFIG. 1A, the waveguide 104 includes a first side 106 and a second side108 opposite the first side 106. Particularly, the first side 106 andthe second side 108 are orthogonal to a height dimension 107 of thewaveguide 104 and parallel to a length dimension 109 of the waveguide104. As such, the set of radiating elements 102 is coupled to the firstside 106 of the waveguide 104.

The waveguide feed 110 is shown coupled to the second side 108 of thewaveguide 104 along the length dimension 109 of the waveguide 104. Inparticular, the waveguide feed 110 is coupled at a center locationbetween a first half of the set of radiating elements 102 and a secondhalf of the set of radiating elements 102. As such, the waveguide feed110 may be aligned orthogonally to the length of the waveguide 104.

During operation of the antenna 100, the waveguide feed 110 isconfigured to transfer electromagnetic energy between the waveguide 104and a component external to the waveguide (e.g., a radar chipset thatprovides and receives radar signals in the form of electromagneticenergy). In some embodiments, the waveguide feed 110 may serve to directenergy one way from the external component to the waveguide 104. Inother embodiments, the waveguide feed 110 is configured to serve as atwo-way component that can direct energy both ways between the waveguide104 and the external component. For example, the waveguide feed 110 maybe coupled to a beamforming network. The beamforming network may coupleto multiple waveguides (e.g., the waveguide 104) and each waveguide mayfurther link to a set of radiating elements. Therefore, in someexamples, multiple sets of radiating elements 102 may form atwo-dimensional array and a single feed 110 may provide electromagneticenergy for a plurality of waveguides, like waveguide 104, that each havea set of radiating elements 102 coupled thereto.

In some examples, the waveguide feed 110 may couple to the waveguide 104at a junction. Particularly, the junction may be configured to dividepower based on geometry of the waveguide feed 110 and the waveguide 104.Additionally, the junction may include a power-dividing component 105(or power divider 156 of FIG. 1B) The power-dividing component 105 mayfunction to split power from the waveguide feed 110 evenly between aleft half of the waveguide 104 and the right half of the waveguide 104.

The antenna 100 is shown with radiating doublets and radiating singletswithin the set of radiating elements 102. In some other examples (notshown), all the antenna elements may be created with radiating doublets.Starting from a first end of the linear array, radiating doublet 112 ispositioned on the first end and followed by radiating doublet 114, afirst radiating singlet 120, a second radiating singlet 122, radiatingdoublet 116, and radiating doublet 118 positioned on the second end. Inthe first configuration shown in FIG. 1A, the radiating singlets 120,122 are positioned together proximate a center of the linear array sucha first set of radiating doublets (i.e., radiating doublets 112, 114) ispositioned outside the first radiating singlet 120 and a second set ofradiating doublets (i.e., radiating doublets 116, 118) is positionedoutside the second radiating singlet 122. As such, the arrangement ofthe first half of radiating elements mirrors the arrangement of thesecond half of radiating elements when viewed from the center of thelinear array. The mirroring arrangements of the halves of radiatingelements establish the symmetry of radiating elements within the lineararray.

By having the radiating elements in a symmetrical arrangement, theantenna system may achieve several benefits. First, by making theantenna symmetrical, the antenna may designed in a more simple manner.Second, the antenna's performance may be improved if the feed is locatedat a symmetrical point. When the antenna is symmetric about the feed, itmay have desirable broadband properties. For example, when aconventional end-fed waveguide antenna is fed with a signal of afrequency other than the exact design frequency, the antenna may sufferfrom beam squint. Beam squint is when the phase of the signal fortransmission is mismatched from the exact design criteria. Beam squintcauses the transmission beam to have a deviation from the designedtransmission direction. By feeding the antenna in the center, the arrayfunctionally acts like two end-fed arrays that are fed with a commonsignal, but from opposite ends. Rather than have a beam squint, thepresent antenna may have a beam widening or narrowing as the frequencyof operation changes.

The center positioning of the radiating singlets 120, 122 within thelinear array may enable each singlet to transmit with moreelectromagnetic energy received through the waveguide 104 from thewaveguide feed 110. The proximate positioning of the radiating singlets120, 122 relative to the waveguide feed 110 may enable moreelectromagnetic energy to enter and transmit through each radiatingsinglet. This arrangement with singlets in the center may be desirablein antennas where the taper profile specifies that the center elementsof an array, here radiating singlets 120, 122, transmit electromagneticsignals with a larger relative amplitude from the other radiatingelements of the array.

In some embodiments, the antenna 100 may include dips under waveguide108 and relative to the waveguide feed 110 that can assist withdirecting energy towards various radiating elements. The dips may differin structure, design, and placement within examples. Further, theantenna 100 may not include the dips at all in other embodiments.

The antenna 100 may further include components not shown in FIG. 1A. Forinstance, the antenna 100 may include a power dividing network definedby the waveguide 104 and configured to divide the electromagnetic energytransferred by the waveguide feed 110 based on a taper profile. Eachradiating element may receive a portion of the electromagnetic energybased on the taper profile. In some examples, the power dividing networkmay unevenly divide the power from the waveguide feed 110. In otherexamples, the power dividing network may evenly divide the power fromthe waveguide feed 110.

FIG. 1B illustrates a second configuration of an antenna. Similar to theantenna 100 in the first configuration, the antenna 130 shown in thesecond configuration includes a set of radiating elements 132, awaveguide 134, and a waveguide feed 140. In other configurations, theantenna 100 may include more or fewer elements.

In the second configuration, the set of radiating elements 132 of theantenna 130 includes a first radiating singlet 150 and a secondradiating singlet 152 positioned on the ends of the linear array ofradiating elements. Particularly, the first radiating singlet 150 ispositioned outside of a first set of radiating doublets (i.e., radiatingdoublets 142, 144) at a first end of the linear array and the secondradiating singlet 152 is positioned outside of a second set of radiatingdoublets (i.e., radiating doublets 146, 148) at a second end of thelinear array. This arrangement with singlets at the ends of the arraymay be desirable in antennas based on a given taper profile. In otherexamples that are not shown, doublets and singlets may be combined inother ways as well.

FIG. 1C illustrates a three-dimensional rendering of the secondconfiguration of the antenna shown in FIG. 1B. As shown in the secondconfiguration, the antenna 130 includes a set of radiating elements, awaveguide 134, and a waveguide feed 140. The radiating elements includesa first radiating singlet 150 and a second radiating singlet 152positioned on opposite ends of the linear array. The antenna 130 furtherincludes radiating doublets 142, 144, 146, 148 positioned in between theradiating singlets 150, 152. As indicated above, the secondconfiguration may be desirable to enable particular operation by theantenna 130 with respect to a taper profile.

The waveguide 134 may be configured in a similar manner as thewaveguides discussed throughout this disclosure. For example, thewaveguide 134 may include various shapes and structures configured todirect electromagnetic power to the various radiating elements (e.g.,radiating singlets 150, 152 and radiating doublets 142, 144, 146, 148)of waveguide 134. Particularly, a portion of electromagnetic wavespropagating through waveguide 134 may be divided and directed by variousrecessed wave-directing members and raised wave-directing members.

The pattern of wave-directing members shown in FIG. 1C is one examplefor the wave-directing members. Based on the specific implementation,the wave-directing members may have different sizes, shapes, andlocations. Additionally, the waveguide may be designed to have thewaveguide ends to be tuned shorts. For example, the geometry of the endsof the waveguides may be adjusted so the waveguide ends act as tunedshorts to prevent reflections of electromagnetic energy within thewaveguide 134.

As on example, as shown in FIG. 1A, the ends of the waveguide 104 mayhave end portions that are approximately quarter of a wavelength long.Similarly, the waveguide 134 of FIG. 1B may include tuned shorts 154 atthe ends of the waveguide. In some examples, when an electromagneticwave reflects off the metallic ends of the waveguide (waveguide 104 orwaveguide 134), it may be reflected 180 degrees out of phase. This 180degree phase shift combined with double the length of the tuned shorts(i.e., ¼ of a wavelength of the tuned short, doubled due to inward andoutward propagation), causes the reflected energy to be in phase withthe energy in the waveguide.

At each junction of respective radiating elements of the waveguide 134,the junction may be considered a two way power divider. A percentage ofthe electromagnetic power may couple into the neck of the respectiveradiating elements and the remaining electromagnetic power may continueto propagate down the waveguide 134. By adjusting the various parametersneck width, heights, and steps) of each respective radiating element,the respective percentage of the electromagnetic power may becontrolled. Thus, the geometry of each respective radiating element maybe controlled in order to achieve the desired power taper. Thus, byadjusting the geometry of each of the offset feed and each respectiveradiating element, the desired phase and power taper for a respectivewaveguide and its associated radiating elements may be achieved.

When the system is being used in a transmission mode, electromagneticenergy may be injected into the waveguide 134 via the waveguide feed140. The waveguide feed 140 may be a port (i.e. a through hole) in abottom metal layer. The waveguide feed 140 may serve as a linkingwaveguide that enables electromagnetic energy to transfer into thewaveguide 134.

As such, an electromagnetic signal may be coupled from outside theantenna unit into the waveguide 134 through the waveguide feed 140. Theelectromagnetic signal may come from a component located outside theantenna unit, such as a printed circuit board, another waveguide, aradar chip, or other signal source. In some examples, the waveguide feed140 may be coupled to another dividing network of waveguides.

When the system is being used in a reception mode, the various radiatingelements may be configured to receive electromagnetic energy from theoutside world. In these examples, the waveguide feed 140 may be used toremove electromagnetic energy from the waveguide 134. Whenelectromagnetic energy is removed from the waveguide 134, it may becoupled into components (e.g., one or more radar chips) for furtherprocessing.

In many traditional examples, a waveguide feed is located at the end ofa waveguide. In the example shown in FIG. 1C, the waveguide feed 140 islocated at a center location that aligns with a center of thesymmetrical linear array of radiating elements. By centrally locatingthe waveguide feed 140, the electromagnetic energy that couples into thewaveguide 134 may be divided more easily. Further, by locating thewaveguide feed 140 at a central position, an antenna unit may bedesigned in a more compact manner.

When electromagnetic energy enters the waveguide 134 from the waveguidefeed 140, the electromagnetic energy may be split in order to achieve adesired radiation pattern. For example, it may be desirable for each ofa series of radiating elements in the linear array to receive apredetermined percentage of the electromagnetic energy from thewaveguide 134. The waveguide may include a power dividing element (notshown) that is configured to split the electromagnetic energy thattravels down each side of the waveguide.

In some examples, the power dividing element may cause the power to bedivided evenly or unevenly between radiating elements. The radiatingelements may be configured to radiate the electromagnetic energy uponreception of a portion of the electromagnetic energy. In some examples,each radiating element may receive approximately the same percentage ofthe electromagnetic energy as each other radiating element. In otherexamples, each radiating element may receive a percentage of theelectromagnetic energy based on a taper profile that specifies apercentage of the energy to be radiated by each doublet or antennaelement.

In some example taper profiles, the radiating elements of the antenna130 that are located closer to the center of waveguide 138 relative tothe waveguide feed 140 may receive a higher percentage of theelectromagnetic energy. In some embodiments, the antenna 130 may includedips under waveguide 138 and relative to the waveguide feed 140 that canassist with directing energy towards various radiating elements. Thedips may differ in structure, design, and placement within examples.Further, the antenna 130 may not include the dips at all in otherembodiments. If electromagnetic energy is injected into the end of thewaveguide 138, it may be more difficult to design the waveguide 138 tocorrectly split power between the various radiating elements. Bylocating the waveguide feed 140 at the central position, a more naturalpower division between the various radiating elements may be achieved.

In some examples, the radiating elements may have an associated taperprofile that specifies the radiating elements in the center shouldreceive a higher percentage of the electromagnetic energy than the otherelements. Because the waveguide feed 140 is located closer to the centerelements, it may be more natural to divide power with elements closestto the waveguide feed 140 receiving higher power. Further, if thewaveguide 138 has the waveguide feed 140 located at the center of thewaveguide 138, the waveguide 138 may be designed in a symmetrical mannerto achieve the desired power division.

In some examples, the antenna 130 may operate in one of two modes. Inthe first mode, the antenna 130 may receive electromagnetic energy froma source for transmission (i.e. operate as a transmission antenna). Inthe second mode, the antenna 130 may receive electromagnetic energy fromoutside of the antenna 130 for processing (i.e. operate as a receptionantenna).

FIG. 2A illustrates a first layer 202 of an antenna 200 that forms a twodimensional array of antenna elements. As shown, the first layer 202includes a first half of a set of waveguide channels 203. The waveguidechannels 203 may include multiple elongated segments 204, each of whichcorresponds to one or more waveguides. As such, at a first end of eachelongated segment 204 may be one or more radiating singlets 206 andradiating doublets 207. Each radiating singlet 206 and radiating doublet207 may have similar sizes or different sizes within examples.

Power may be used to feed a corresponding amount of electromagneticwaves (i.e., energy) into the antenna 200 with one or more through-holesthat may be the location where these waves are fed into the apparatus.In line with the description above, the single channel/segment of thewaveguide channels 203 that includes the input port may be referred toherein as an input waveguide channel.

Upon entering the antenna 200, electromagnetic waves may generallytravel in both the +x and −x directions, as the feed coupleselectromagnetic energy into a center of the waveguides with respect tothe x direction. The array may function to divide up the electromagneticwaves and propagate respective portions of the waves to respective firstends of each elongated segment 204. More specifically, the waves maycontinue to propagate in the +x and −x directions after leaving thearray toward the radiating singlets 206 and radiating doublets 207. Inline with the description above, the array section of the waveguidechannels may be referred to herein as wave-dividing channels.

As the portions of the electromagnetic waves reach wave-directingmembers at the first end of each elongated segment 204 of the waveguidechannels 203, the wave-directing members may propagate throughrespective sub-portions of the electromagnetic energy to a second halfof the waveguide channels (i.e., in the +z direction, as shown). Forinstance, the electromagnetic energy may first reach a wave-directingmember that is recessed, or machined further into the first metal layer202 (i.e., a pocket). That recessed member may be configured topropagate a smaller fraction of the electromagnetic energy than each ofthe subsequent members further down the first end, which may beprotruding members rather than recessed members.

Further, each subsequent member may be configured to propagate a greaterfraction of the electromagnetic waves travelling down that particularelongated segment 204 at the first end than a prior member. As such, themember at the far end of the first end may be configured to propagatethe highest fraction of electromagnetic waves. Each wave-directingmember 206 may take various shapes with various dimensions. In otherexamples, more than one member none of the members) may be recessed.Still other examples are possible as well. In addition, varyingquantities of elongated segments are possible.

A second metal layer may contain a second half of the one or morewaveguide channels, where respective portions of the second half of theone or more waveguide channels include an elongated segmentsubstantially aligned with the elongated segment of the first half ofthe one or more waveguide channels and, at an end of the elongatedsegment, at least one pair of through-holes partially aligned with theat least one wave-directing member and configured to radiateelectromagnetic waves propagated from the at least one wave-directingmember out of the second metal layer.

Within examples, the elongated segment of the second half may beconsidered to substantially align with the elongated segment of thefirst half when the two segments are within a threshold distance, orwhen centers of the segments are within a threshold distance. Forinstance, if the centers of the two segments are within about ±0.051 mmof each other, the segment may be considered to be substantiallyaligned.

In another example, when the two halves are combined (i.e., when the twometal layers are joined together), edges of the segments may beconsidered to be substantially aligned if an edge of the first half of asegment and a corresponding edge of the second half of the segment arewithin about ±0.051 mm of each other.

In still other examples, when joining the two metal layers, one layermay be angled with respect to the other layer such that their sides arenot flush with one another. In such other examples, the two metallayers, and thus the two halves of the segments, may be considered to besubstantially aligned when this angle offset is less than about 0.5degrees.

In some embodiments, the at least one pair of through-holes may beperpendicular to the elongated segments of the second half of the one ormore waveguide channels. Further, respective pairs of the at least onepair of through-holes may include a first portion and a second portion.As such, a given pair of through-holes may meet at the first portion toform a single channel. That single channel may be configured to receiveat least the portion of electromagnetic waves that was propagated by acorresponding wave-directing member and propagate at least a portion ofelectromagnetic waves to the second portion. Still further, the secondportion may include two output ports configured as a doublet and may beconfigured to receive at least the portion of electromagnetic waves fromthe first portion of the pair of through-holes and propagate at leastthat portion of electromagnetic waves out of the two output ports.

FIG. 2B illustrates an assembled view of the antenna 200. The antenna200 may include the first metal layer 202, the second metal layer 210,and a third metal layer 212. The second metal layer 210 may include aplurality of holes 216 (through-holes and/or blind-holes) configured tohouse alignment pins, screws, and the like. The first metal layer 202and the third metal layer 212 may include a plurality of holes as well(not shown) that are aligned with the holes 216 of the second metallayer 210.

As shown in FIG. 2B, the antenna 200 may include a set of radiatingelements 214A, 214B, 214C, 214D arranged in a linear array. The quantityand arrangement of the radiating elements 214A-214D can differ withinexamples. In addition, the dimension of each radiating element candiffer. Further, in such an example embodiment, these dimensions, inaddition to or alternative to other dimensions of the example antenna200, may be machined with no less than about a 0.51 mm error, though inother embodiments, more or less of an error may be required. Otherdimensions of the OEWG array are possible as well.

In some embodiments, the first, second, and third metal layers 202, 210,212 may be machined from aluminum plates (e.g., about 6.35 mm stock). Insuch embodiments, the first metal layer 202 may be at least 3 mm inthickness (e.g., about 5.84 mm to 6.86 mm). Further, the second metallayer and third metal layer 210, 212 may be machined from a 6.35 mmstock to a thickness of about 3.886 mm. Other thicknesses for layers arepossible as well. Additionally, in some examples, these metal layers202, 210, 212 may be made through a metal-plated injection moldingprocess. In this process, the layers may be made with plastic throughinjection molding and coated with metal (either fully metal covered orselectively metal covered).

In some embodiments, the joining of the metal layers 202, 210, 212 mayresult in an air gap or other discontinuity between mating surfaces oftwo layers. In such embodiments, this gap or continuity should beproximate to (or perhaps as close as possible to) a center of the lengthof the antenna apparatus and may have a size of about 0.05 mm orsmaller.

FIG. 3 illustrates a wave-radiating doublet of an example antenna, inaccordance with an example embodiment. More specifically, FIG. 3illustrates a cross-section of an example DOEWG 300. As noted above, aDOEWG 300 may include a horizontal feed (i.e., channel), a vertical feed(i.e. a doublet neck), and a wave-directing member 304. The verticalfeed may configured to couple energy from the horizontal feed to twooutput ports 302, each of which is configured to radiate at least aportion of electromagnetic waves out of the DOEWG 300. The horizontalfeed may be a waveguide section, such as the examples shown in FIG. 1A,FIG. 1B, and FIG. 1C.

In some embodiments, one or more DOEWG may include a backstop atlocation 306. Particularly, the backstop 306 may be on the left or rightside depending on the DOEWG. DOEWGs that come before the last DOEWG maysimply be open at location 306 and electromagnetic waves may propagatethrough that location 306 to subsequent DOEWGs. For example, a pluralityof DOEWGs may be connected in series where the horizontal feed is commonacross the plurality of DOEWGs. FIG. 3 further shows various parametersthat may be adjusted to tune the amplitude and/or phase of anelectromagnetic signal that couples into the radiating element.

In order to tune a DOEWG such as DOEWG 300, the vertical feed width,vfeed_a, and various dimensions of the step 304 (e.g., dw, dx, and dz1)may be tuned to achieve different fractions of radiated energy out theDOEWG 300. The step 304 may also be referred to as a reflectingcomponent as it reflects a portion of the electromagnetic waves thatpropagate down the horizontal feed into the vertical feed. Further, insome examples, the height dz1 of the reflecting component may benegative, that is may extend below the bottom of the horizontal feed.Similar tuning mechanisms may be used to tune the offset feed as well.For example, the offset feed may include any of the vertical feed width,vfeed_a, and various dimensions of the step (e.g., dw, dx, and dz1) asdiscussed with respect to the radiating element.

In some examples, each output port 302 of the DOEWG 300 may have anassociated phase and amplitude. In order to achieve the desired phaseand amplitude for each output port 302, various geometry components maybe adjusted. As previously discussed, the step (reflecting component)304 may direct a portion of the electromagnetic wave through thevertical feed. In order to adjust an amplitude associated with eachoutput port 302 of a respective DOEWG 300, a height associated with eachoutput port 302 may be adjusted. Further, the height associated witheach output port 302 could be the height or the depths of this feedsection of output port 302, and not only could be a height or depthadjustment but it could be a multiplicity of these changes or steps orascending or descending heights or depths in general.

As shown in FIG. 3, height dz2 and height dz3 may be adjusted to controlthe amplitude with respect to the two output ports 302. The adjustmentsto height dz2 and height dz3 may alter the physical dimensions of thedoublet neck (e.g. vertical feed of FIG. 3A). The doublet neck may havedimensions based on the height dz2 and height dz3. Thus, as the heightdz2 and height dz3 are altered for various doublets, the dimensions ofthe doublet neck (i.e. the height of at least one side of the doubletneck) may change. In one example, because height dz2 is greater thanheight dz3, the output port 302 associated with (i.e. located adjacentto) height dz2 may radiate with a greater amplitude than the amplitudeof the signal radiated by the output port 302 associated with heightdz3.

Further, in order to adjust the phase associated with each output port302, steps may be introduced for each output port 302. The steps may belocated on the flat sides of the output port 302 and adjust the heightof dz2 and dz3 in a stepped manner. The steps in the height may cause aphase of a signal radiated by the output port 302 associated with thestep to change. Thus, by controlling both the height and the stepsassociated with each output port 302, both the amplitude and the phaseof a signal transmitted by the output port 302 may be controlled. Invarious examples, the steps may take various forms, such as acombination of up-steps and down-steps. Additionally, the number ofsteps may be increased or decreased to control the phase.

The above-mentioned adjustments to the geometry may also be used toadjust a geometry of the offset feed where it connects to the waveguide.For example, heights, widths, and steps may be adjusted or added to theoffset feed in order to adjust the radiation properties of the system.An impedance match, phase control, and/or amplitude control may beimplemented by adjusting the geometry of the offset feed.

In some examples, an antenna may be constructed from a metal-platedpolymer structure. The polymer may be formed through an injectionmolding process and coated with metal to provide the desiredelectromagnetic properties. FIG. 4 illustrates an example isometriccross-section view of a polymer-based waveguide 460 having a metallicportion 453A, 453B that may form the antenna described herein. Theexample waveguide 460 is formed with a top portion 452 and a bottomportion 454. The top portion 452 and a bottom portion 454 are coupled atseam 456. The seam 456 corresponds to a position where two layers coupletogether. The waveguide includes an air-filled cavity 458. Within cavity458, electromagnetic energy propagates during the operation of waveguide460. The waveguide 460 may also include a feed 459. Feed 459 can be usedto provide electromagnetic energy to cavity 458 in waveguide 460.Alternatively or additionally, feed 459 may be used to allowelectromagnetic energy to leave waveguide 450. The feed 459 may be alocation where electromagnetic energy is fed into or removed from thepresent antenna. In other examples, the feed 459 may be a location wherea waveguide receives energy from a different waveguide section of theantenna, such as the splitting or combining ports described with respectto FIGS. 1A and 1C. The example waveguide 460 of FIG. 4 features seam456 at the middle point of the height of cavity 458. In variousembodiments, the top portion 452 and a bottom portion 454 may be coupledtogether at various different positions along an axis of the waveguide.

As shown in FIG. 4, the top portion 452 and the bottom portion 454 mayhave a respective metallic portion 453A, 453B. The metallic portion 453Aof the bottom portion 454 and the metallic portion 453B of the topportion 452 may each be formed through a plating process. As previouslydiscussed, both the top portion 452 and the bottom portion 454 may bemade of a polymer. The respective metallic portions 453A, 453B may beplated onto the RF surfaces, such as the internal portion of cavity 458and the port 459. Thus, when the top portion 452 is brought into contactwith the bottom portion 454, there is an electrical coupling of therespective metal portions. In the example shown in FIG. 4, only the RFsurfaces (i.e., the surfaces in which electromagnetic energy come incontact) are plated. In other examples, additional surfaces beyond justthe RF surfaces may be plated as well. Further, additional disclosurefor a “Plated, injection Molded, Automotive Radar Waveguide Antenna”disclosed in U.S. patent application Ser. No. 15/219,423, filed Jul. 26,2016 is hereby incorporated by reference in its entirety.

FIG. 5 is a flowchart of an example method 500 to radiateelectromagnetic energy. It should be understood that other methods ofoperation not described herein are possible as well.

It should also be understood that a given application of such an antennamay determine appropriate dimensions and sizes for various machinedportions of the two metal layers described above (e.g., channel size,metal layer thickness, etc.) and/or for other machined (or non-machined)portions/components of the antenna described herein. For instance, asdiscussed above, some example radar systems may be configured to operatewith W-band electromagnetic wave frequency of 77 GHz, which correspondsto millimeter electromagnetic wave length. At this frequency, thechannels, ports, etc. of an apparatus fabricated by way of method 400may be of given dimensions appropriated for the 77 GHz frequency. Otherexample antennas and antenna applications are possible as well.

Although the blocks are illustrated in a sequential order, these blocksmay also be performed in parallel, and/or in a different order thanthose described herein. Also, the various blocks may be combined intofewer blocks, divided into additional blocks, and/or removed based uponthe desired implementation.

At block 502, the method 500 includes feeding electromagnetic energy toa center of a waveguide by a waveguide feed. The waveguide feed may becoupled to the second side of the waveguide at a center location betweena first half of a set of radiating elements and a second half of the setof radiating elements. For instance, the waveguide feed may be coupledto the second side of the waveguide along the length dimension of thewaveguide. The waveguide feed represents a waveguide capable oftransferring (i.e., feeding) electromagnetic energy to the center (oranother portion) of another waveguide or multiple waveguides.

In some examples, the first half of the radiating elements may include afirst set of radiating doublets and a first radiating singlet. Thesecond half of the radiating elements may include a second set ofradiating doublets and a second radiating singlet. For instance, thefirst set of radiating doublets and the second set of radiating doubletsmay each include two radiating doublets.

In some antenna configurations, the first and second radiating singletsare positioned together in the center of the linear array of radiatingelements, such as in the configuration shown in FIG. 1A. In such aconfiguration, the sets of radiating doublets are positioned outside ofthe radiating singlets within the linear array. In other antennaconfigurations, the first and second radiating singlets are positionedon the ends of the linear array of radiating elements, such as in theconfiguration shown in FIG. 1B and FIG. 1C. In such a configuration, thesets of radiating doublets re positioned inside the radiating singletswithin the linear array.

At block 504, the method 500 includes propagating electromagnetic energy(e.g., 77 GHz millimeter electromagnetic waves) via the waveguidebetween (i) each of a plurality of radiating elements and (ii) awaveguide feed. The radiating elements are configured to radiateelectromagnetic energy and arranged symmetrically in a linear array.

In some examples, the geometry of the waveguide may include a heightdimension and a length dimension such that the first and second sides ofthe waveguide are orthogonal to the height dimension and parallel to thelength dimension. As such, the radiating elements may be coupled to thefirst side of the waveguide. For example, a waveguide may have astraight shape and the radiating elements may be aligned along thelength of the waveguide.

At block 506, the method 500 includes, for each respective radiatingelement, providing a portion of the propagating electromagnetic energy.For example, the electromagnetic energy from the waveguide feed may bedivided based on a taper profile. Particularly, each radiating elementof the plurality of radiating elements may receive a portion of theelectromagnetic energy based on the taper profile.

In some examples, the electromagnetic energy is divided evenly. In otherexamples, dividing the electromagnetic energy from the waveguide feedbased on a taper profile unevenly divides the power from the waveguidefeed. In further examples, dividing the electromagnetic energy from thewaveguide feed further involves a beamforming network dividing theelectromagnetic energy to a plurality of waveguides.

At block 508, the method 500 includes radiating at least a portion ofthe coupled electromagnetic energy via each radiating element. Eachradiating element radiates a portion of the coupled electromagneticenergy based on an associated amplitude and phase for each respectiveradiating element defined by the taper profile.

FIG. 6 illustrates a three layer center-fed antenna configuration, inaccordance with example embodiments. As shown in the three layercenter-fed antenna configuration, the antenna 600 includes a set ofradiating elements 602, a waveguide 604, and a feed waveguide 606. Inother configurations, the antenna 600 can have other elements, such asmore or fewer radiating elements.

The antenna 600 represents an antenna configuration that utilizes a feedwaveguide 606 positioned center relative the waveguide 604 and the setof radiating elements 602 (i.e., at a central alignment relative to thelinear array of radiating elements 602). As such, the feed waveguide 606may connect to a feed port that supplies electromagnetic energy to orfrom an element (such as a radar chip or another external component)located outside of the antenna. The electromagnetic energy propagatesthrough the feed waveguide 606 into waveguide 604 to each of the set ofradiating elements 602 in a symmetrical distribution. This type ofdistribution can enable balanced performance of the set of radiatingelements 602.

The set of radiating elements 602 are shown with the radiating elements608, 610, 612, 614, 616, and 618. These radiating elements 608-618 areshown arranged in a linear array along a top surface of the waveguide604. Particularly, each radiating element 608-618 (or a subset of theradiating elements 608-618) may radiate electromagnetic energy receivedfrom the waveguide 604 as radar signals into the environment of theantenna 600. In addition, one or more of the radiating elements 608-618may receive radar signals that reflected off one or more surfaces in theenvironment and back towards the antenna 600. The radiating elements608-618 are shown as radiating doublets, but can have otherconfigurations within examples (e.g., singlets, triplets) similar toother antenna configurations described herein.

As shown in FIG. 6, the antenna 600 may include multiple layers, such asa first layer 640, a second layer 642, and a third layer 644. Theselayers may be made out of various materials, such as one or more typesof metal. For instance, the layers may be generated using a CNC process.When two of the layers are coupled together, the plane at which the twolayers couple together forms a seam. For instance, the first layer 640and the second layer 642 are shown coupled together forming seam 636 andthe second layer 642 and the third layer 644 are coupled togetherforming seam 638. Seams 636-638 may represent the junction betweendifferent layers of the antenna 600. Although three layers are shown forthe antenna 600, other embodiments may include more or fewer layers. Forinstance, another example antenna may be configured with four layers. Insome examples, each of the first layer 640, the second layer 642, andthe third layer 644 are made from machined metal. As such, the waveguide604 may be air filled.

The first layer 640 includes a first portion 620 of the feed waveguide606. The first portion 620 may be machined as part of the first layer640. As shown, the first portion 620 of the feed waveguide 606 iscoupled to the second portion 622 of the feed waveguide 606 creating aseam 636. As shown, the feed waveguide 606 forms a structure that iscoupled to a first waveguide portion 620 that causes propagation ofelectromagnetic energy in a direction parallel to the set of radiatingelements 602 within the horizontal waveguide including the first portion620.

In the example shown in FIG. 6, the first portion 620 is coupled to thesecond portion 622 of the feed waveguide 606 such that an alignment ofthe first portion 620 and the second portion 622 includes an offset 621.The offset 621 may influence the propagation of electromagnetic energyin the feed waveguide 606, such as impedance matching or phaseadjustment. As such, the size of the offset 621 may vary depending onthe desired impact on the electromagnetic energy transferred within thefeed waveguide 606 to and from the waveguide 604.

When the second layer 642 and the third layer 644 are coupled together,the waveguide 604 is formed. Particularly, the second layer 642 includesa first portion 603 of the waveguide 604 and the third layer 644includes a second portion 605 of the waveguide 604. Thus, when thesecond layer 642 and the third layer 644 are coupled together, thewaveguide 604 is formed by the coupling of the first portion 603 and thesecond portion 605. This coupling creates a seam 638 that extends alonga center of the waveguide 604. The waveguide 604 may be an air-filledwaveguide and may further split and combine electromagnetic energy.Particularly, the combination of the second layer 642 and the thirdlayer 644 may form a beamforming network.

The third layer 644 further includes a set of radiating elements 602.The set of radiating elements 602 are shown in a linear array. In otherexamples, the set of radiating elements 602 may be arranged differently,such as another two dimensional (2D) or three dimensional (3D) array.

The waveguide 604 is configured to guide electromagnetic energy betweenthe set of radiating elements 602 and the feed waveguide 606. As shownin FIG. 6, the waveguide includes a first side 609 and a second side 607opposite the first side 609. Particularly, the first side 609 and thesecond side 607 are orthogonal to a height dimension 648 of thewaveguide 604 and parallel to a length dimension 646 of the waveguide604. As such, the set of radiating elements 602 are shown coupled to thefirst side 609 of the waveguide 604.

The feed waveguide 606 is shown coupled to the second side 607 of thewaveguide 604. In particular, the second portion 622 of the feedwaveguide 606 is coupled to the second portion 605 of the waveguide 604at a coupling point 623. As shown in FIG. 6, the coupling point 623aligns with a center 613 of the linear array of radiating elements 602.With the center alignment between the feed waveguide 606 relative to thecenter 613 of the linear array, the feed waveguide 606 and the waveguide604 may transfer electromagnetic energy symmetrically to each radiatingelement 608-618. Thus, unlike an end-fed antenna that utilizes a feedwaveguide coupled to an end of the waveguide, the central position ofthe feed waveguide 606 may help propagate and distribute electromagneticenergy uniformly to the radiating elements 608-618.

During operation of the antenna 600, the feed waveguide 606 transferselectromagnetic energy between the waveguide 604 and a componentexternal to the waveguide 604 (e.g., a radar chipset that provides andreceives radar signals in the form of electromagnetic energy). In someembodiments, the feed waveguide 606 may serve to direct energy one wayfrom the feed port to the waveguide 604. In other embodiments, the feedwaveguide 606 is configured to serve as a two-way component that candirect energy both ways between the waveguide 604 and the externalcomponent (e.g., the feed port, a radar chip). For example, the feedwaveguide 606 may be coupled to a beamforming network. The beamformingnetwork may couple to multiple waveguides (e.g., the waveguide 604) andeach waveguide may further link to one or more radiating elements.Therefore, in some examples, multiple sets of radiating elements 602 mayform a 2D array and the feed waveguide 606 may provide electromagneticenergy for multiple waveguides, like the waveguide 604, that each have aset of radiating elements coupled thereto.

In some examples, the feed waveguide 606 may couple to the waveguide 604at a junction. Particularly, the junction may be configured to dividepower based on geometry of the feed waveguide 606 and the waveguide 604.

In some embodiments, the antenna 600 may include one or more dips thedips 624, 626, 628, 630, 632, and 634) under the waveguide 604 (e.g.,the second side 607 of the waveguide 604) and relative to the feedwaveguide 606 that can assist with directing energy towards variousradiating elements. The dips 624-634 may differ in structure, design,and placement within examples. Further, the antenna 600 may not includethe dips at all in other embodiments.

The antenna 600 may further include components not shown in FIG. 6. Forinstance, the antenna 600 may include a power dividing network locatedin a plane defined by one of the seams and configured to divide theelectromagnetic energy transferred by the feed waveguide 606 based on ataper profile. Each radiating element 608-618 may receive a portion ofthe electromagnetic energy based on the taper profile. In some examples,the power dividing network may unevenly divide the power from the feedwaveguide 606. In other examples, the power dividing network may evenlydivide the power from the feed waveguide 606.

FIG. 7 illustrates a three-dimensional rendering of the three layercenter-fed antenna configuration illustrated in FIG. 6, in accordancewith example embodiments. As shown in the center fed configuration, theantenna 600 includes a set of radiating elements, a waveguide 604, and afeed waveguide 606. As indicated above, this configuration may bedesirable to enable particular operation by the antenna 600 with respectto a taper profile.

The waveguide 604 may be configured in a similar manner as thewaveguides discussed throughout this disclosure. For example, thewaveguide 604 may include various shapes and structures configured todirect electromagnetic power to the various radiating elements.Particularly, a portion of electromagnetic waves propagating throughwaveguide 604 may be divided and directed by various recessedwave-directing members and raised wave-directing members.

The pattern of wave-directing members shown in FIG. 7 is one example forthe wave-directing members 624-634. Based on the specificimplementation, the wave-directing members may have different sizes,shapes, and locations. Additionally, the waveguide may be designed tohave the waveguide ends to be tuned shorts. For example, the geometry ofthe ends of the waveguides may be adjusted so the waveguide ends act astuned shorts to prevent reflections of electromagnetic energy within thewaveguide 604.

At each junction of respective radiating elements of the waveguide 604,the junction may be considered a two way power divider. A percentage ofthe electromagnetic power may couple into the neck of the respectiveradiating elements and the remaining electromagnetic power may continueto propagate down the waveguide 604. By adjusting the various parametersneck width, heights, and steps) of each respective radiating element,the respective percentage of the electromagnetic power may becontrolled. Thus, the geometry of each respective radiating element maybe controlled in order to achieve the desired power taper. Thus, byadjusting the geometry of each of the offset feed and each respectiveradiating element, the desired phase and power taper for a respectivewaveguide and its associated radiating elements may be achieved.

When the system is being used in a transmission mode, electromagneticenergy may be injected into the waveguide 604 via the feed waveguide606. The feed waveguide 606 may couple to a port (i.e. a through hole)in a bottom metal layer. The feed waveguide 606 may serve as a linkingwaveguide that enables electromagnetic energy to transfer into thewaveguide 604. As such, an electromagnetic signal may be coupled fromoutside the antenna 600 into the waveguide 604 through the feedwaveguide 606. The electromagnetic signal may come from a componentlocated outside the antenna unit, such as a printed circuit board,another waveguide, a radar chip, or other signal source. In someexamples, the feed waveguide 606 may be coupled to another dividingnetwork of waveguides.

When the system is being used in a reception mode, the various radiatingelements may be configured to receive electromagnetic energy from theoutside world. In these examples, the feed waveguide 606 may be used toremove electromagnetic energy from the waveguide 604. Whenelectromagnetic energy is removed from the waveguide 604, it may becoupled into one or more external components (e.g., one or more radarchips) for further processing.

In the example shown in FIG. 7, the feed waveguide 606 is located at alocation (e.g., a center coupling point) that aligns with a center ofthe symmetrical linear array of radiating elements. By centrallylocating the feed waveguide 606, the electromagnetic energy that couplesinto the waveguide 604 may be divided more easily. Further, by locatingthe feed waveguide 606 at a central position, an antenna unit may bedesigned in a more compact manner relative to an end-fed antenna unit.

When electromagnetic energy enters the waveguide 604 from the feedwaveguide 606, the electromagnetic energy may be split in order toachieve a desired radiation pattern. For example, it may be desirablefor each of a series of radiating elements in the linear array toreceive a predetermined percentage of the electromagnetic energy fromthe waveguide 604. The waveguide may include a power dividing element(not shown) that is configured to split the electromagnetic energy thattravels down each side of the waveguide.

In some examples, the power dividing element may cause the power to bedivided evenly or unevenly. One or more of the set of radiating elements602 may be configured to radiate the electromagnetic energy uponreception of a portion of the electromagnetic energy. In some examples,each radiating element may receive approximately the same percentage ofthe electromagnetic energy as each other radiating element. In otherexamples, each radiating element may receive a percentage of theelectromagnetic energy based on a taper profile.

In some example taper profiles, the radiating elements 608-618 of theantenna 600 that are located closer to the center of the waveguide 604relative to the feed waveguide 606 may receive a higher percentage ofthe electromagnetic energy. If electromagnetic energy is injected intothe end of the waveguide, it may be more difficult to design thewaveguide to correctly split power between the various radiatingelements. By locating the feed waveguide 606 at the central position, amore natural power division between the various radiating elements maybe achieved.

In some examples, the radiating elements may have an associated taperprofile that specifies the radiating elements in the center shouldreceive a higher percentage of the electromagnetic energy than the otherelements. Because the feed waveguide 606 is located closer to the centerelements (e.g., radiating elements 612, 614), it may be more natural todivide power with elements closest to the feed waveguide 606 receivinghigher power. Further, if the waveguide 604 has the feed waveguide 606located at the center of the waveguide 604, the waveguide 604 may bedesigned in a symmetrical manner to achieve the desired power division.

FIG. 8 is a flowchart of an example method 800 to radiateelectromagnetic energy. It should be understood that other methods ofoperation not described herein are possible as well.

Although the blocks are illustrated in a sequential order, these blocksmay also be performed in parallel, and/or in a different order thanthose described herein. Also, the various blocks may be combined intofewer blocks, divided into additional blocks, and/or removed based uponthe desired implementation.

At block 802, the method 800 includes feeding, at an antenna system,electromagnetic energy to a center of a waveguide by a feed waveguide.In some examples, a first layer of the antenna system includes a firstportion of the feed waveguide coupled to a feed port.

At block 804, the method 800 includes propagating electromagnetic energy(e.g., 77 GHz millimeter electromagnetic waves) via the waveguidebetween (i) the feed waveguide and (ii) each radiating element in a setof radiating elements arranged in a linear array. In some examples, asecond layer of the antenna system includes a second portion of the feedwaveguide and a first portion of the waveguide. The first portion of thefeed waveguide is coupled to the second portion of the feed waveguidesuch that the feed waveguide causes propagation of electromagneticenergy in a direction parallel to a seam between the first layer and thesecond layer. In addition, the second portion of the feed waveguide iscoupled to the first portion of the waveguide at a coupling point. Forexample, the antenna system may resemble the antenna configuration 600shown in FIGS. 6 and 7.

In some examples, the set of radiating elements are arranged in thelinear array and may include a first subset of radiating elementsextending a first direction from the center of the linear array and asecond subset of radiating elements extending a second direction fromthe center of the linear array. For instance, a first quantity ofradiating elements in the first subset of radiating elements equals asecond quantity of radiating elements in the second subset of radiatingelements. The linear array may also include other arrangements andquantities of radiating elements.

At block 806, the method 800 includes, for each radiating element,providing a portion of the propagating electromagnetic energy. Forexample, the electromagnetic energy from the waveguide feed may bedivided based on a taper profile. Particularly, each radiating elementof the plurality of radiating elements may receive a portion of theelectromagnetic energy based on the taper profile.

In some examples, the electromagnetic energy is divided evenly. In otherexamples, dividing the electromagnetic energy from the waveguide feedbased on a taper profile unevenly divides the power from the waveguidefeed. In further examples, dividing the electromagnetic energy from thewaveguide feed further involves a beamforming network dividing theelectromagnetic energy to a plurality of waveguides.

In some examples, a third layer of the antenna system includes a secondportion of the waveguide and the set of radiating elements arranged inthe linear array. Each radiating element is coupled to the secondportion of the waveguide and the coupling point aligns with a center ofthe linear array.

At block 808, the method 800 includes radiating portions of the coupledelectromagnetic energy via each radiating element. Each radiatingelement radiates a portion of the coupled electromagnetic energy basedon an associated amplitude and phase for each respective radiatingelement defined by the taper profile.

FIG. 9 is a flowchart of an example method 900 to receiveelectromagnetic energy. It should be understood that other methods ofoperation not described herein are possible as well.

Although the blocks are illustrated in a sequential order, these blocksmay also be performed in parallel, and/or in a different order thanthose described herein. Also, the various blocks may be combined intofewer blocks, divided into additional blocks, and/or removed based uponthe desired implementation.

At block 902, the method 900 may involve receiving electromagneticenergy at radiating elements of a linear array located in a third layerof an antenna. For example, an antenna may include multiple layers andthe third layer may include a set of radiating elements similar to theantenna configuration illustrated in FIGS. 6 and 7. One or moreradiating elements may receive electromagnetic energy that correspondsto reflections of radar signals that reflected off a surface in theenvironment of the antenna.

At block 904, the method 900 may involve coupling the receivedelectromagnetic energy into a waveguide. In some examples, the antennamay be configured such that a first portion of the waveguide is in asecond layer of the antenna and a second portion of the waveguide is inthe third layer of the antenna.

At block 906, the method 900 may involve coupling at least a portion ofthe received electromagnetic energy into a feed waveguide. The antennaconfiguration may include a first portion of the feed waveguide in afirst layer of the antenna and a second portion of the feed waveguidecoupled to the first portion of the waveguide at a coupling point in thesecond layer of the antenna. Particularly, the first portion of the feedwaveguide may be coupled to the second portion of the feed waveguidesuch that the feed waveguide causes propagation of electromagneticenergy in a direction parallel to a seam between the first layer and thesecond layer of the antenna. The coupling point of the second layer maybe in alignment with a center of the linear array.

At block 908, the method 900 may involve coupling the receivedelectromagnetic energy from the feed waveguide to an external component.For instance, a portion of the electromagnetic energy may be propagatedthrough the feed waveguide into an external component, such as a radarchip.

It should also be understood that a given application of such an antennamay determine appropriate dimensions and sizes for various machinedportions of the two metal layers described above (e.g., channel size,metal layer thickness, etc.) and/or for other machined (or non-machined)portions/components of the antenna described herein. For instance, asdiscussed above, some example radar systems may be configured to operatewith W-band electromagnetic wave frequency of 77 GHz, which correspondsto millimeter electromagnetic wave length. At this frequency, thechannels, ports, etc. of an apparatus fabricated by way of method 400may be of given dimensions appropriated for the 77 GHz frequency. Otherexample antennas and antenna applications are possible as well.

It should be understood that other shapes and dimensions of thewaveguide channels, portions of the waveguide channels, sides of thewaveguide channels, wave-directing members, and the like are possible aswell. In some embodiments, a rectangular shape of waveguide channels maybe highly convenient to manufacture, though other methods known or notyet known may be implemented to manufacture waveguide channels withequal or even greater convenience.

It should be understood that arrangements described herein are forpurposes of example only. As such, those skilled in the art willappreciate that other arrangements and other elements (e.g. machines,apparatuses, interfaces, functions, orders, and groupings of functions,etc.) can be used instead, and some elements may be omitted altogetheraccording to the desired results. Further, many of the elements that aredescribed are functional entities that may be implemented as discrete ordistributed components or in conjunction with other components, in anysuitable combination and location.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the scope beingindicated by the following claims.

What is claimed is:
 1. An antenna system comprising: a first layerhaving a first portion of a feed waveguide coupled to a feed port; asecond layer having a second portion of the feed waveguide and a firstportion of a waveguide, wherein the first portion of the feed waveguideis coupled to the second portion of the feed waveguide such that thefeed waveguide causes propagation of electromagnetic energy in adirection parallel to a seam between the first layer and the secondlayer, and wherein the second portion of the feed waveguide is coupledto the first portion of the waveguide at a coupling point; and a thirdlayer having a second portion of the waveguide and a set of radiatingelements arranged in a linear array, wherein each radiating element iscoupled to the second portion of the waveguide, and wherein the couplingpoint of the second layer is in alignment with a center of the lineararray.
 2. The antenna system of claim 1, wherein the set of radiatingelements arranged in the linear array comprises a first subset ofradiating elements extending a first direction from the center of thelinear array and a second subset of radiating elements extending asecond direction from the center of the linear array.
 3. The antennasystem of claim 2, wherein a first quantity of radiating elements in thefirst subset of radiating elements equals a second quantity of radiatingelements in the second subset of radiating elements.
 4. The antennasystem of claim 1, wherein each radiating element in the set ofradiating elements is a radiating doublet.
 5. The antenna system ofclaim 1, wherein the waveguide symmetrically divides electromagneticenergy received from the feed waveguide.
 6. The antenna system of claim1, wherein each of the first layer, the second layer, and the thirdlayer are made from machined metal, and wherein the waveguide is airfilled.
 7. The antenna system of claim 1, wherein the first portion ofthe feed waveguide is coupled to the second portion of the feedwaveguide such that an offset is in an alignment of the first portionand the second portion of the feed waveguide.
 8. The antenna system ofclaim 1, further comprising: a power dividing network defined by thewaveguide and configured to divide the electromagnetic energy propagatedby the feed waveguide based on a taper profile, wherein each radiatingelement receives a portion of the electromagnetic energy based on thetaper profile.
 9. The antenna system of claim 1, wherein the feedwaveguide is coupled to a beamforming network, wherein the beamformingnetwork is coupled to a plurality of respective waveguides and eachwaveguide includes a plurality of radiating elements.
 10. The antennasystem of claim 1, wherein the feed waveguide is coupled to thewaveguide at a junction, and wherein the junction is configured todivide power based on geometry of at least one of the feed waveguide andthe waveguide.
 11. A method of radiating a radar signal comprising:feeding, at an antenna system, electromagnetic energy to a center of awaveguide by a feed waveguide, wherein a first layer of the antennasystem includes a first portion of the feed waveguide coupled to a feedport; propagating electromagnetic energy via the waveguide between (i)the feed waveguide and (ii) each radiating element in a set of radiatingelements arranged in a linear array, wherein a second layer of theantenna system includes a second portion of the feed waveguide and afirst portion of the waveguide, wherein the first portion of the feedwaveguide is coupled to the second portion of the feed waveguide suchthat the feed waveguide causes propagation of electromagnetic energy ina direction parallel to a seam between the first layer and the secondlayer, and wherein the second portion of the feed waveguide is coupledto the first portion of the waveguide at a coupling point; for eachradiating element, providing a portion of the propagatingelectromagnetic energy, wherein a third layer of the antenna systemincludes a second portion of the waveguide and the set of radiatingelements arranged in the linear array, wherein each radiating element iscoupled to the second portion of the waveguide, and wherein the couplingpoint is in alignment with a center of the linear array; and radiatingportions of the propagating electromagnetic energy via each radiatingelement.
 12. The method of claim 11, wherein the set of radiatingelements arranged in the linear array comprises a first subset ofradiating elements extending a first direction from the center of thelinear array and a second subset of radiating elements extending asecond direction from the center of the linear array.
 13. The method ofclaim 12, wherein a first quantity of radiating elements in the firstsubset of radiating elements equals a second quantity of radiatingelements in the second subset of radiating elements.
 14. The method ofclaim 11, wherein each radiating element in the set of radiatingelements is a radiating doublet.
 15. The method of claim 11, whereineach of the first layer, the second layer, and the third layer are madefrom machined metal, and wherein the waveguide is air filled.
 16. Themethod of claim 11, wherein the first portion of the feed waveguide iscoupled to the second portion of the feed waveguide such that an offsetis in an alignment of the first portion and the second portion of thefeed waveguide.
 17. The method of claim 11, wherein for each radiatingelement, providing the portion of the propagating electromagnetic energycomprises: dividing the electromagnetic energy from the feed waveguidebased on a taper profile, wherein each radiating element receives aportion of the electromagnetic energy based on the taper profile. 18.The method of claim 17, wherein dividing electromagnetic energy from thefeed waveguide further comprises a beamforming network dividing theelectromagnetic energy to a plurality of waveguides.
 19. A method ofreceiving a radar signal comprising: receiving electromagnetic energy atone or more radiating elements of a linear array located in a thirdlayer of an antenna; coupling the received electromagnetic energy into awaveguide, wherein a first portion of the waveguide is in a second layerof the antenna and a second portion of the waveguide is in the thirdlayer of the antenna; coupling at least a portion of the receivedelectromagnetic energy into a feed waveguide, wherein a first portion ofthe feed waveguide is in a first layer of the antenna and a secondportion of the feed waveguide is coupled to the first portion of thewaveguide at a coupling point in the second layer of the antenna,wherein the first portion of the feed waveguide is coupled to the secondportion of the feed waveguide such that the feed waveguide causespropagation of electromagnetic energy in a direction parallel to a seambetween the first layer and the second layer of the antenna, and whereinthe coupling point of the second layer is in alignment with a center ofthe linear array; and coupling the at least the portion of the receivedelectromagnetic energy from the feed waveguide to an external component.20. The method of receiving the radar signal of claim 19, wherein thefirst portion of the feed waveguide is coupled to the second portion ofthe feed waveguide such that an offset is in an alignment of the firstportion and the second portion of the feed waveguide.